Systems and methods for network entry management

ABSTRACT

A method for network entry management for use in a base station. The method includes steps of broadcasting multiple carriers, wherein the carriers are classified into fully configured carriers and partially configured carriers, the fully configured carrier includes at least one primary synchronization channel (P-SCH) and at least one secondary synchronization channel (S-SCH), and the partially configured carrier includes at least one P-SCH and does not include the S-SCH.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of application Ser. No. 12/837,956,filed Jul. 16, 2010, now U.S. Pat. No. 8,265,625, which claims thebenefit of U.S. Provisional Application No. 61/235,480 filed Aug. 20,2009, the entireties of which are incorporated by reference herein

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure relates generally to systems and methods for networkentry management, and, more particularly to systems and methods fornetwork entry management that provide a hierarchical synchronizationchannel design for a multi-carrier system to reduce network entrylatency.

2. Description of the Related Art

Recently, mobile stations, such as mobile devices having wirelesscommunication capabilities have become more and more popular. Due toincreased convenience and functions of the mobile devices, these deviceshave become basic necessities of life.

In a multi-carrier system, when a mobile station powers on, it will scanvarious carriers based on known channel rasters. In 3GPP 36.101 v9.0.0,the center raster is 100 kHz for all bands. A mobile station may scansynchronization channels on every 100 kHz in each band to discover ifthere is a 3GPP system. When a band 1 ranges from 2110 MHz to 2170 MHz,a mobile station will scan from 3GPP systems on the carriers 2110 MHz,2110.1 MHz, 2110.2 MHz, . . . , 2169.9 MHz. Multi-carrier systems may becomposed of fully configured carriers and partially configured/extensioncarriers. The fully configured carriers can operate standalone. Thepartially configured/extension carriers can not operate standalone, andcan not be used for network entry. Currently, hierarchicalsynchronization channels (SCH) have been adopted by some orthogonalfrequency division modulation (OFDM) systems, such as IEEE 802.16m and3GPP LTE. Hierarchical SCH is composed of a primary synchronizationchannel (P-SCH) and secondary a synchronization channel (S-SCH). TheP-SCH and S-SCH may be time division multiplexed. The P-SCH is used fortiming acquisition and frequency synchronization, and is used for symbolboundary detection. The S-SCH may carry a cell identity (cell ID) orpartial cell ID information, e.g. Physical ID in a 3GPP LTE. The S-SCHmay be used for channel estimation.

Generally, a frame structure may include two P-SCHs and two S-SCHs, anda broadcasting channel (BCH) follows either the P-SCH or S-SCH. The BCHcan carry system information, such as a bandwidth, identity, frameconfigurations, location of control channels, and other systeminformation. The SCH is generally used as an identity for a station tolock onto the system. When a system adopts the hierarchical SCH, amobile station may detect the P-SCH to synchronize system timing andcenter frequency, and then the mobile station will detect the S-SCH toacquire complete cell IDs. After, a mobile station can retrieve systeminformation via the BCH. It is understood that, a mobile station willleave the carrier and scan for another carrier if the mobile station cannot detect the P-SCH, S-SCH or BCH. It is noted that, a mobile stationwill scan every carrier within each band to try to lock onto the system.If no related information or mechanism can be provided in thehierarchical SCH, network entry latency will be serious.

IEEE C802.16m_(—)08_(—)1093 proposes a method to reduce network entrylatency. It applies different P-SCHs to the fully configured carrier andthe partially configured carrier. Therefore, a mobile station can detectthe P-SCH to verify if a current carrier is the fully configuredcarrier. If the current carrier is a partially configured carrier, amobile station will skip the carrier to scan for another carrier, suchthat network entry latency can be reduced. However, in IEEEC802.16m_(—)08_(—)1093, the number of P-SCHs has increased. If onlythree sequences are set for the P-SCHs, it will cause at least a 33%detection complexity overhead. The structure also wastes resources forthe S-SCH.

BRIEF SUMMARY OF THE INVENTION

Systems and methods for network entry management are provided.

An embodiment of a system for network entry management includes a basestation and a mobile station. The base station broadcasts on multiplecarriers. The carriers include at least a first carrier including atleast one P-SCH and does not include an S-SCH, wherein the P-SCH may beused for timing acquisition and frequency synchronization, and the S-SCHmay be used for cell identification. The mobile station scans the firstcarrier, and checks whether a P-SCH is broadcasted on the first carrier.If a P-SCH is broadcasted on the first carrier, the mobile stationchecks whether an S-SCH is broadcasted on the first carrier. If no S-SCHis broadcasted on the first carrier, the mobile station scans a secondcarrier broadcasted by the base station.

An embodiment of a system for network entry management at least includesa base station. The base station broadcasts on multiple carriers. Thecarriers are classified into fully configured carriers and partiallyconfigured carriers. The fully configured carrier includes at least oneP-SCH and at least one S-SCH, and the partially configured carrierincludes at least one P-SCH, and does not include the S-SCH. The P-SCHmay be used for timing acquisition and frequency synchronization, andthe S-SCH may be used for cell identification.

An embodiment of a system for network entry management at least includesa mobile station. The mobile station scans a first carrier withinmultiple carriers, and checks whether a P-SCH is broadcasted on thefirst carrier. If a P-SCH is broadcasted on the first carrier, themobile station retrieves recommended information in the P-SCH, selects asecond carrier within the carriers based on the recommended information,and scans for the second carrier.

In an embodiment of a method for network entry management, multiplecarriers are broadcasted by a base station, wherein the carriers includeat least a first carrier including at least one P-SCH, and does notinclude an S-SCH, and the P-SCH may be used for timing acquisition andfrequency synchronization, and the S-SCH may be used for a cellidentification. The first carrier is scanned by a mobile station, and itis checked whether a P-SCH is broadcasted on the first carrier. If aP-SCH is broadcasted on the first carrier, it is checked whether anS-SCH is broadcasted on the first carrier. If no S-SCH is broadcasted onthe first carrier, a second carrier broadcasted by the base station isscanned by the mobile station.

In an embodiment of a method for network entry management for use in abase station, multiple carriers are broadcasted, wherein the carriersare classified into fully configured carriers and partially configuredcarriers. The fully configured carrier includes at least one P-SCH andat least one S-SCH, and the partially configured carrier includes atleast one P-SCH, and does not include the S-SCH. The P-SCH may be usedfor timing acquisition and frequency synchronization, and the S-SCH maybe used for cell identification.

In an embodiment of a method for network entry management for use in amobile station, a first carrier within multiple carriers is scanned. Itis checked whether a P-SCH is broadcasted on the first carrier. If aP-SCH is broadcasted on the first carrier, it is checked whether anS-SCH is broadcasted on the first carrier. If no S-SCH is broadcasted onthe first carrier, recommended information in the P-SCH is retrieved, asecond carrier within the carriers is selected based on the recommendedinformation, and the second carrier is scanned.

In some embodiments, the recommended information may be a channel spaceor a coarse raster, or a carrier configuration. The carrierconfiguration indicates whether a band including the first carrier has afully configured carrier, and the fully configured carrier is in ahigher frequency, or the fully configured carrier is in a lowerfrequency.

Methods for network entry management may take the form of a program codeembodied in a tangible media. When the program code is loaded into andexecuted by a machine, the machine becomes an apparatus for practicingthe disclosed method.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood by referring to thefollowing detailed description with reference to the accompanyingdrawings, wherein:

FIG. 1 is a schematic diagram illustrating an embodiment of a system fornetwork entry management of the invention;

FIG. 2 is a schematic diagram illustrating an embodiment of a basestation of the invention;

FIG. 3 is a schematic diagram illustrating an embodiment of a mobilestation of the invention;

FIG. 4 is a schematic diagram illustrating an embodiment of a framestructure of a fully configured carrier of the invention;

FIG. 5A is a schematic diagram illustrating an embodiment of a framestructure of a partially configured carrier of the invention;

FIG. 5B is a schematic diagram illustrating another embodiment of aframe structure of a partially configured carrier of the invention;

FIG. 5C is a schematic diagram illustrating another embodiment of aframe structure of a partially configured carrier of the invention;

FIG. 6 is a flowchart of an embodiment of a method for network entrymanagement for a base station of the invention;

FIG. 7 is a flowchart of an embodiment of a method for network entrymanagement for a mobile station of the invention; and

FIG. 8 is a flowchart of another embodiment of a method for networkentry management for a mobile station of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Systems and methods for network entry management are provided.

FIG. 1 is a schematic diagram illustrating an embodiment of a system fornetwork entry management of the invention.

The system for network entry management 100 comprises a base station 110and a plurality of mobile stations (132, 134 and 136). FIG. 2 is aschematic diagram illustrating an embodiment of a base station of theinvention. The base station 110 may be an electronic device implementedwith a multi-carrier system. It is understood that, the basic protocols,concept and related terminologies of the multi-carrier system are wellknown in the art, and omitted here. The base station 110 comprises atransceiver unit 112 and a processing unit 114. The processing unit 114can enable the transceiver unit 112 to broadcast multiple carriers 120comprising fully configured carriers and partially configured carriers.It is understood that, the partially configured carrier may havedifferent names, such as an extension carrier, in various systems. Inthe present application, the partially configured carrier is used forexplanation, and the present invention is not limited thereto. Detailsof fully configured carriers and partially configured carriers will bediscussed later.

FIG. 3 is a schematic diagram illustrating an embodiment of a mobilestation of the invention. The mobile station 300 may be an electronicdevice having wireless communications capability. The mobile station 300comprises a transceiver unit 310 and a processing unit 320. Theprocessing unit 320 can scan carriers via the transceiver unit 310,perform related analysis with the carriers, and accordingly lock onto anetwork provided by the base station 110. Related details will bediscussed further in the following paragraphs.

As described, the system is a multi-carrier system with fully configuredcarriers and partially configured carriers. The fully configuredcarriers can operate standalone. The partially configured/extensioncarriers can not operate standalone, and can not be used for networkentry. In the present invention, the hierarchical SCH composed of P-SCH,S-SCH, and BCH can be used for carrier configuration in themulti-carrier system. The P-SCH may be used for timing acquisition andfrequency synchronization, and may be used for symbol boundarydetection. The S-SCH may carry cell identity (cell ID) or partial cellID information, e.g. Physical ID in 3GPP LTE. The S-SCH may be used forchannel estimation. The BCH can carry system information, such asbandwidth, identity, frame configurations, location of control channels,and others.

In the present invention, the frame structure of the fully configuredcarrier comprises at least one P-SCH and at least one S-SCH. FIG. 4 is aschematic diagram illustrating an embodiment of a frame structure of afully configured carrier of the invention. In the embodiment of FIG. 4,the fully configured carrier 400 is composed of S-SCHs (402 and 406) andP-SCHs (404 and 408). It is understood that, the fully configuredcarrier 400 in FIG. 4 is similar to that in conventional arts. A mobilestation can detect both synchronization channels (P-SCH and S-SCH) inthe fully configured carrier 400 and enter the network provided by thesystem.

In the present invention, the frame structure of the partiallyconfigured carrier comprises at least one P-SCH, and has no S-SCH. FIG.5A is a schematic diagram illustrating an embodiment of a framestructure of a partially configured carrier of the invention. As shownin FIG. 5A, the partially configured carrier 500 is composed of P-SCHs(502 and 504). Since the S-SCH is removed from the partially configuredcarrier 500, a mobile station cannot detect the S-SCH through thecarrier, and will ignore the carrier. To save radio resources for datatransmission, in some embodiments, the system can transmit data at theposition for S-SCH in the partially configured carrier since no S-SCHshould be transmitted in the partially configured carrier. Further, insome embodiments, if several P-SCHs are within a frame, the amount ofP-SCHs can also be adjusted to save radio resources for datatransmission. For example, the P-SCH 502 in the partially configuredcarrier 500 of FIG. 5A can be removed, as shown in FIG. 5B. For example,the P-SCH 504 in the partially configured carrier 500 of FIG. 5A can beremoved, as shown in FIG. 5C. Similarly, the position of the removedP-SCH can be used to transmit data.

It is understood that, in some embodiments, the P-SCH may have 2 timestime domain repeated characteristic, and the P-SCH may use a Zadoff Chucode or generalized chirp like code. In some embodiments, the P-SCH canbe applied in frequency domain interleave preambles, and an FDM/CDMbased synchronization channel. It is understood that, in someembodiments, the P-SCH may use MIMO schemes, such as cyclic delaydiversity and/or cluster-based phase rotation. It is understood that, insome embodiments, the S-SCH may have 3 times time domain repeatedcharacteristics or 5 times time domain repeated characteristics.Similarly, the S-SCH may use a Zadoff Chu code or generalized chirp likecode. In some embodiments, the S-SCH may use the MIMO scheme, such ascyclic delay diversity, or the FSTD MIMO scheme.

It is noted that, in some embodiments, the P-SCH in the partiallyconfigured carrier may comprise recommended information. The recommendedinformation may be a channel space, a coarse raster, or a carrierconfiguration. In the channel space, for example, when three sequencesare used for the P-SCH in the partially configured carrier, one sequencecan be set as a first channel space, another sequence can be set as asecond channel space, and the other sequence can be set as a thirdchannel space. In an example of 3GPP LTE, one sequence can be set as a1.4 MHz channel space, another sequence can be set as a 3 MHz channelspace, and the other sequence can be set as a 5 MHz/10 MHz/20 MHzchannel space. A mobile station can select and scan for another carrierbased on the referent channel space to largely avoid redundant carrierscan. It is noted that, in the LTE case, the channel space can befurther restricted to be used in the current band or adjacent carriers.In a coarse raster, for example, when three sequences are used for theP-SCH in the partially configured carrier, one sequence can be set as asmall bandwidth scanning step, another sequence can be set as a mediumbandwidth scanning step, and the other sequence can be set as a largebandwidth scanning step. For example, one sequence can be set as a 1.4MHz coarse raster, another sequence can be set as a 3 MHz coarse raster,and the other sequence can be set as a 5 MHz coarse raster. In someembodiments, the center frequency can be defined to be allocated between+XHz and −XHz to the scanned frequency. In a carrier configuration, forexample, when three sequences are used for the P-SCH in the partiallyconfigured carrier, one sequence can be set to indicate that no fullyconfigured carrier is in a band, another sequence can be set to indicatethat the fully configured carrier is in a higher frequency, and theother sequence can be set to indicate that the fully configured carrieris in a lower frequency. In some embodiments, the P-SCH in the partiallyconfigured carrier may indicate that a carrier currently being scannedis a partially configured carrier. The mobile station can select andscan for another carrier based on the recommended information retrievedfrom the P-SCH in the partially configured carrier. Related details willbe discussed later.

FIG. 6 is a flowchart of an embodiment of a method for network entrymanagement for a base station of the invention.

In step S602, the base station broadcasts at least one fully configuredcarrier. As described, the fully configured carrier comprises at leastone P-SCH and at least one S-SCH. It is noted that, in some embodiment,the base station will also broadcast system information, such asbandwidth, identity, frame configurations, location of control channels,and others in a BCH. In step S604, the base station broadcasts at leastone partially configured carrier. Similarly, the partially configuredcarrier comprises at least one P-SCH, and has no S-SCH. Further, in someembodiment, the base station can further embed recommended informationand/or an indication into the P-SCH in the partially configured carrier.Similarly, the recommended information may be a channel space, a coarseraster, or a carrier configuration, and the indication may indicate thata carrier is currently being scanned is a partially configured carrier.

FIG. 7 is a flowchart of an embodiment of a method for network entrymanagement for a mobile station of the invention. In the embodiment, thepartially configured carrier comprises at least one P-SCH, and has noS-SCH.

In step S702, the mobile station scans for a carrier within the carriersbroadcasted by a base station. In step S704, it is determined whether aP-SCH is within the carrier. If no P-SCH is broadcasted on the carrier(No in step S704), in step S706, the mobile station scans for anothercarrier, and the procedure goes to step S704. If at least one P-SCH isbroadcasted on the carrier (Yes in step S704), in step S708, the mobilestation acquires information from the P-SCH to synchronize system timingand center frequency. In step S710, it is determined whether an S-SCH iswithin the carrier. If no S-SCH is broadcasted on the carrier (No instep S710), in step S706, the mobile station scans for another carrier,and the procedure goes to step S704. It is understood that, asdescribed, since the S-SCH is removed from the partially configuredcarrier broadcasted by the base station, the mobile station cannotdetect the S-SCH through the carrier, and will ignore the carrier. If atleast one S-SCH is broadcasted on the carrier (Yes in step S710), instep S712, the mobile station acquires a cell identity from the S-SCH.Then, in step S714, the mobile station detects the BCH from the carrier,and retrieves system information, such as bandwidth, identity, frameconfigurations, location of control channels, and others from the BCH,and in step S716, accordingly enters a network provided by the basestation implementing the multi-carrier system.

FIG. 8 is a flowchart of another embodiment of a method for networkentry management for a mobile station of the invention. In theembodiment, the partially configured carrier comprises at least oneP-SCH, and has no S-SCH, and the mobile station can select and scan foranother carrier based on recommended information recorded in the P-SCHin the partially configured carrier.

In step S802, the mobile station scans for a carrier within the carriersbroadcasted by a base station. In step S804, it is determined whether aP-SCH is within the carrier. If no P-SCH is broadcasted on the carrier(No in step S804), in step S806, the mobile station scans for anothercarrier, and the procedure goes to step S804. If at least one P-SCH isbroadcasted on the carrier (Yes in step S804), in step S808, the mobilestation acquires information from the P-SCH to synchronize system timingand center frequency. In step S810, it is determined whether an S-SCH isbroadcasted on the carrier. If no S-SCH is broadcasted on the carrier(No in step S810), in step S812, the mobile station acquires recommendedinformation from the P-SCH in the partially configured carrier, and instep S814, selects and scans another carrier based on the retrievedrecommended information, and the procedure goes to step S804. Similarly,the recommended information may be a channel space, a coarse raster, ora carrier configuration. If at least one S-SCH is broadcasted on thecarrier (Yes in step S810), in step S816, the mobile station acquires acell identity from the S-SCH. Then, in step S818, the mobile stationdetects the BCH from the carrier, and retrieves system information, suchas bandwidth, identity, frame configurations, location of controlchannels, and others from the BCH, and in step S820, accordingly entersa network provided by the base station implementing the multi-carriersystem.

As described, the P-SCH in the partially configured carrier may have anindication to indicate whether the carrier is a partially configuredcarrier. In some embodiments, once the indication in the P-SCH in acarrier is detected by the mobile station, the mobile station will leavethe carrier and scan another carrier. It is understood that, in someembodiments, the mobile station scans another carrier based on therecommended information.

Therefore, the systems and methods for network entry management canprovide a hierarchical synchronization channel design for amulti-carrier system to reduce network entry latency and save radioresources.

Methods for network entry management, or certain aspects or portionsthereof, may take the form of a program code (i.e., executableinstructions) embodied in tangible media, such as floppy diskettes,CD-ROMS, hard drives, or any other machine-readable storage medium,wherein, when the program code is loaded into and executed by a machine,such as a computer, the machine thereby becomes an apparatus forpracticing the methods. The methods may also be embodied in the form ofa program code transmitted over some transmission medium, such aselectrical wiring or cabling, through fiber optics, or via any otherform of transmission, wherein, when the program code is received andloaded into and executed by a machine, such as a computer, the machinebecomes an apparatus for practicing the disclosed methods. Whenimplemented on a general-purpose processor, the program code combineswith the processor to provide a unique apparatus that operatesanalogously to application specific logic circuits.

While the invention has been described by way of example and in terms ofpreferred embodiment, it is to be understood that the invention is notlimited thereto. Those who are skilled in this technology can still makevarious alterations and modifications without departing from the scopeand spirit of this invention. Therefore, the scope of the presentinvention shall be defined and protected by the following claims andtheir equivalents.

What is claimed:
 1. A method for network entry management for use in abase station, comprising: broadcasting multiple carriers, wherein thecarriers are classified into fully configured carriers and partiallyconfigured carriers, the fully configured carrier includes at least oneprimary synchronization channel (P-SCH) and at least one secondarysynchronization channel (S-SCH), and the partially configured carrierincludes at least one P-SCH and does not include the S-SCH.
 2. Themethod of claim 1, further comprising embedding recommended informationinto the P-SCH in the partially configured carrier, in which a mobilestation selects and scans a specific carrier within the carriers basedon the recommended information.
 3. The method of claim 2, wherein therecommended information comprises a channel space or a coarse raster, ora carrier configuration, wherein the carrier configuration indicateswhether a band including a carrier currently being scanned has a fullyconfigured carrier, and whether a fully configured carrier is in ahigher frequency, or a fully configured carrier is in a lower frequency.4. The method of claim 1, further comprising embedding an indicationinto the P-SCH in the partially configured carrier, in which a mobilestation scans another carrier based on the indication, wherein theindication indicates that a carrier currently being scanned is apartially configured carrier.